##x^6sqrtx##
First you should understand that a square root is a ##1/2## exponent
in reality. That’s why ##sqrt(x^2)=x^1##
because its the same as ##x^(2/2)=x^1##
The problem is much easier if you convert your expression from
##sqrt(x^13)## to ##x^(13/2)##
You then simplify the exponent to ##x^(6 1/2)## which is equivalent to ##x^6sqrtx##
I hope this helps!